It is already known, from the specification of French published Patent Application FR2443657A, to provide a water header of this type which has an elongated open face and which is adapted to be assembled over a header plate or collector which is arranged in a substantially horizontal position, such that a liquid can flow in the header between a first end and second end of the latter, with the liquid covering the header plate.
Such a water header is adapted to be sealingly connected to the upper end of a heat exchanger body, which typically consists of a bundle comprising a multiplicity of heat exchange tubes arranged so as to extend generally vertically. The open face of the header body is then assembled on the header plate (or perforated plate), in which the upper ends of the tubes in the bundle are sealingly received. The lower ends of the tubes are generally joined to another water header, through a header plate of the latter.
In the header described in the above mentioned French Patent Specification, removable transverse grids are provided, these being spaced apart between the two ends of the header, so that air which is entrained by the liquid flowing in the heat exchanger can become separated from the liquid in the chambers which are defined between these grids. In this way, such a header enables the liquids flowing in the heat exchanger to be de-gassed, this liquid commonly being the cooling liquid for an internal combustion engine. The gases separated from the liquid then accumulate in the upper part of the fluid header, which also serves as an expansion vessel or chamber.
However, this known type of water header has a certain number of drawbacks. First of all, it is expensive to make, because it requires the provision of the grids which have to be fitted into the header body before the latter is assembled onto the header plate of the heat exchanger. In addition, because each of these grids is in the form of a mesh having a large number of holes, it tends to encourage the formation of bubbles which are detrimental to proper functioning of the heat exchanger. Furthermore, these grids give rise to energy losses in the flow of the liquid in the heat exchanger.